I would like to know more about the Kurma avatar of Vishnu. I know that Vishnu took the form of a tortoise to facilitate Samudra Manthana. Although, no other details are known. The Wikipedia article is not of much help.

Astrologically, Kurma avatar is associated with Shani Graha.

Are there any scriptures which go into more details about this Avatar of Vishnu?

For those interested, here is a question which talks about the temples of Kurma avatar.